DYNAMIC CORRELATION-FUNCTION OF POLYMER DENSITY-FLUCTUATIONS IN CONCENTRATED-SOLUTIONS

The time-dependent correlation function of concentration fluctuations in a polymer solution in the regime of entanglements is studied theoretically. Three stages of relaxation of concentration fluctuations are predicted. The first stage is due to cooperative deformation of entangelement network; its characteristic rate is τ-1c∝q2N0 (here q is the wave vector and N is the number of links per polymer chain). The second stage corresponds to a Rouse-type relaxation of macromolecular tension along the "tube". The last stage, which is due to reptation motion of macromolecules, is characterized by a spectrum of relaxation times between τrept and τmax. Here τmax∝N3 is the longest reptation time, and the time τrept depends on q and N in the following way: τrept∝N3q4 for b-1≫q≫(Rb) -1 2; τrept∝N2q 0 for (Rb) -1 2≫q≫R-1; τrept∝N1q-2 for R-1≫q≫ b R2 (here R = N 1 2a is the size of a macromolecule, b is the effective tube diameter). © 1990.